1. Field of Invention
The techniques and apparatus described herein relate to piezoelectric electromechanical devices such as piezoelectric electromechanical transistors.
2. Discussion of the Related Art
Resonators are widely used in communication applications as filter components and as signal sources at selected frequencies. Some communication devices use conventional LC tank resonator circuits which have difficulty meeting the insertion loss, quality factor and out-of-band rejection capabilities needed to meet today's filtering requirements. A significant proportion of cellular telephones currently in use have large passive mechanical components such as Surface Acoustic Wave (SAW) and Film Bulk Acoustic Resonator (FBAR) components which have seen very little miniaturization over the past few years.
Microelectromechanical resonators can be produced having quality factors (Q) that are often several orders of magnitude higher than those of LC circuits, and offer the potential for integration using microfabrication. As the size of transistors continues to shrink, transistor threshold frequencies have increased, enabling transceiver circuitry to be designed to operate at frequencies in the range of tens of GHz. Conventional microelectromechanical resonators are not well-suited to such high frequency applications at least in part because of their capacitive coupling, which causes undesirable capacitive feedthrough between the input and output terminals at high frequencies.